The leaf margins in Ephemerum serratum vary markedly, from barely serrate to long spinose. In general, plants from eastern North America tend to be more strongly serrate than plants from California and Oregon, although barely serrate plants from the east as well as distinctly serrate plants from the west have been seen. Mature capsules frequently persist with only the remnants of leaves remaining, the distal portions of the leaves apparently eroded away. Rarely, thick-walled, elongate, brown structures occur on the protonemata and they may serve as diaspores.